Cytokines and the brain: implications for clinical psychiatry.

This article reviews recent developments in cytokine biology that are relevant to clinical psychiatry. The authors reviewed English-language literature of the last 15 years that pertains to the biology of cytokines with emphasis on central nervous system effects in general and psychiatric disorders in particular. Growing evidence suggests that, in addition to providing communication between immune cells, specific cytokines play a role in signaling the brain to produce neurochemical, neuroendocrine, neuroimmune, and behavioral changes. This signaling may be part of a generalized, comprehensive mechanism to mobilize resources in the face of physical and/or psychological stress and to maintain homeostasis. The clinical implications of these findings are far-reaching and include a possible role for cytokines in the pathophysiology of specific psychiatric disorders such as major depression, schizophrenia, and Alzheimer's disease. The effects of cytokines in the central nervous system may provide a possible mechanism for the "sickness behavior" of patients with severe infection or cancer, as well as for the neuropsychiatric adverse effects of treatment with interferons and interleukins. A better understanding of the role of cytokines in various brain activities will enhance knowledge of specific psychobiological mechanisms in health and disease and provide opportunities for novel treatment interventions.